Cell therapy methods have been developed in order to enhance the host immune response to tumors, viruses and bacterial pathogens. Cell therapy methods often involve the ex-vivo activation and expansion of T-cells. Examples of these type of treatments include the use of tumor infiltrating lymphocyte (TIL) cells (see U.S. Pat. No. 5,126,132 issued to Rosenberg), cytotoxic T-cells (see U.S. Pat. No. 6,255,073 issued to Cai, et al.; and U.S. Pat. No. 5,846,827 issued to Celis, et al.), expanded tumor draining lymph node cells (see U.S. Pat. No. 6,251,385 issued to Tennan), and various other lymphocyte preparations (see U.S. Pat. No. 6,194,207 issued to Bell, et al.; U.S. Pat. No. 5,443,983 issued to Ochoa, et al.; U.S. Pat. No. 6,040,177 issued to Riddell, et al.; U.S. Pat. No. 5,766,920 issued to Babbitt, et al.).
For maximum effectiveness of T-cells in cell therapy protocols, the ex vivo activated T-cell population should be in a state of maximal activation upon infusion. Efforts for developing improved methods for producing more effective T-cells for use in cell therapy protocols have focused on the ex-vivo activation methods. However, ex-vivo activated cells need to be harvested and administered to patients to have a therapeutic effect. The harvesting of the T-cells removes them from the activating stimuli available in the ex-vivo cultures. Therefore, the longer the time from harvest to infusion, the lower the quality of the T-cells.
There is a need to develop T-cell formulations for infusion that maintain the cells in a state that can maximally orchestrate an immune response to cancer, infectious diseases and other disease states at both the time of infusion and while circulating in the blood. Efforts to maintain the activation state of T-cells at the time of infusion have most commonly involved the formulation of the T-cells with exogenous IL-2. Systemic IL-2 administration to patients has also been used to maintain the activation state of T-cells post-infusion. However, exogenous IL-2 administration is extremely toxic to patients and has not resulted in significant benefit to patients undergoing T-cell infusions.